1. Field of the Invention
The present invention is in the field of method and apparatus for power-operation of a gate. More particularly, the present invention relates to a power-drive apparatus for selectively moving a gate between opened and closed positions, and which has a mode of operation in which a human may manually teach the gate operator both a fully opened and fully closed position for the gate, as well as a desired profile of accelerations, decelerations, and velocities for the gate as it moves between these fully opened and fully closed positions.
2. Related Technology
It is conventional to move a gate, such as a gate controlling vehicular access to a parking lot, to a gated community, or to private land, for example, by means of a power-drive unit which moves the gate between fully opened and fully closed positions. The gate may swing about a vertical hinge axis to open and close, or may move horizontally along a guide way. Ordinarily, the power-drive unit for such gates includes an electric motor with a speed reduction drive train coupled to the gate to effect its movement between the opened and closed positions.
Conventionally, the limits of movement of a gate are set using conventional limit switches. Alternatively, the mechanism of the gate operator may be configured such that opened and closed position for the gate are set by the mechanical operation constraints of the mechanism itself. That is, a physical abutment or gate movement stop may be used to set the limits of movement of the gate at one or both of the fully opened and fully closed positions. When the gate encounters the physical stops, the drive motor stalls, the stalled motor draws an increased level of current, and a current sensing circuit associated with the drive motor senses this stall-current and shuts off the drive motor. Alternatively, an encoder providing a pulse train indicative of gate movement may be used. In this case, when the gate encounters a physical movement stop, the pulse train also stops, and the end of this pulse train can be sensed by, for example, using a time-out timer to detect when the interval between pulses exceeds a certain threshold. In this case, a controller for the gate will determine the locations of the physical gate movement stops in terms of pulse count numbers, and use this information in future operations of the gate.
Owners of gate operators which depend upon contact of the gate with a physical gate movement stop will likely object to the jarring and noise such impact produces. Many owners are quite unhappy with the conventional gate operator mechanisms because the gate literally bangs or slams against the stops with each operation of the gate between opened and closed positions. Even the gate operators which reset the positions of the limit stops and use an encoder will hang against the stops on the first operations of the gate, or after a system reset.
Conventional power-drive gate operators are seen in U.S. Pat. Nos. 4,234,833; 4,429,264; 4,916,860; 5,136,809; and 5,230,179. Of these conventional teachings, the '833 patent purports to disclose a gate operator with a form of motor shaft rotation encoder formed by flats on the drive motor shaft, which flats are viewed by an optical sensor. The sensor generates an output signal indicative of gate movement as represented by rotation of the drive motor shaft. Apparently, the owner of this device must determine the extent of gate movement between its fully opened and fully closed positions, and program this movement information into the gate operator in the form of an encoder pulse count number.
The '860, '809, and '179 patents are related to one another and appear to use a form of encoder employing magnetic sensors mounted to a stationary plate member and cooperative magnets mounted to a pulley rotating with an output shaft of the gate operator. The drive shaft of the motor for this device appears to be connected to the gate at all times. This device does not appear to have a self-teaching function.
The '264 patent appears to relate to a gate operator which employs an encoder to determine gate movement between its fully opened and fully closed positions, and which does not employ any limit switches. This gate operator appears also not to have a teaching mode. In this gate operator, the gate is initially driven against its physical stops in order to stall the motor of the gate operator and to allow the control system for this gate operator to set beginning and end values for a full-travel pulse count register entry. Thereafter, the gate operator counts encoder pulses as the gate moves between its fully opened and fully closed positions, counting pulses up in each direction of gate movement until the pulse count matches the value in the full-travel register. This gate operator does not appear to have any provision for easing into contact with physical stops, or for easing through a potential obstruction contact zone at a reduced speed so that contacts with physical objects (i.e., with the physical stops or an obstruction) are not at full gate speed. The gate of this '264 patent thus may crash against the physical stops or an obstruction, and may even "bounce off" such objects, as the patent explains.
None of the gate operators in the related technology allow a human to simply teach the gate operator where the physical stops of gate movement are located, to show the gate operator where selected limits (limit positions, not physical movement stops) of gate movement are located for fully open and fully closed positions, or to show the gate operator the speed of movement desired for the gate, or the locations and magnitudes of accelerations and decelerations desired for the gate by manually moving the gate between these positions and at velocities and accelerations which are the human's choice to be replicated by the gate operator. Also, none of the convention gate operators appear to provide for an alternative mode of learning for such an operator in which a human who perhaps is too frail to physically move the gate in a preferred velocity and acceleration profile, or who simply doesn't want to have to physically move the gate to teach the operator a desired profile, can instead use a manual input device to the gate operator so that in a learning mode the gate is power driven according to a profile input from the manual input device, and the gate operator learns this profile for future use. Further, none of the conventional gate operators provide for a variety of preprogrammed default gate movement profiles which can be selected by the user in the event that a user-programmed profile is not used.